Galvanic Method Research Articles

Research about Cu-Zn Catalysts for Urea Synthesis Depending on Structure Difference

As the global population increases, there’s a growing demand for crops, leading to increased nitrogen fertilizers. In particular, urea (CO(NH3)2) accounts for over 70% of the world's nitrogen fertilizers, highlighting the importance of its production. Urea is typically produced through the Bosch–Meiser process, involving the reaction of CO2 and NH3 under harsh conditions (>180 ℃, ~150 bar). This process consumes significant energy and emits CO2 and NOx. In contrast, electrochemical urea synthesis offers a sustainable alternative when using renewable electricity from wind or solar and can be operated under mild conditions. Notably, co-reduction of CO2 and NO3 allows for the utilization of CO2 and NO3 produced in industrial processes, leading to potential energy and cost savings due to their higher reactivity and solubility compared to N2. Additionally, skipping the NH3 generation process offers advantages in reducing transportation and storage costs.Nevertheless, the synthesis of urea through the co-reduction of CO2 and NO3 involves a complex 16-electron reaction, where C-N coupling plays a crucial role. Furthermore, undesirable by-products such as NH3 or NO2 can also be generated during the urea synthesis process, emphasizing the importance of controlling selectivity. Recent studies have proposed catalysts designed to facilitate C-N coupling by adjusting the binding energies of C and N intermediates on the catalyst surface to reduce energy barriers. Copper (Cu) and zinc (Zn) are known materials with appropriate adsorption energies for C and N intermediates, respectively. Therefore, the goal is to design catalysts that effectively perform the roles of C intermediate binding sites and N intermediate binding sites by combining these two elements appropriately. Among various catalyst synthesis methods, the galvanic displacement method is known for forming dendritic structures. Hence, we aim to synthesize CuZn binary catalysts via galvanic displacement, adjusting the catalyst's structure to understand its role in urea production.Furthermore, in an H-type cell, it faces the challenge of CO2's low solubility in aqueous-fed systems and the difficulty of mass transfer due to the distance between the gas and the electrode. Additionally, supplying nitrate ions (NO3 –) requires additional solution. Therefore, we utilized a flow cell to directly supply CO2 gas through the gas diffusion electrode, overcoming the limitations of CO2 solubility and mass transfer. We will also supply NO3 – through the catholyte chamber. Thus, in the catholyte chamber, it is effective to establish a solid (catalysts)-liquid (NO3 –)-gas (CO2) three-phase boundary, which is predicted to promote C-N bonding.In this process, Zn was electrodeposited onto a pretreated microporous layer on carbon paper (MPL/CP) in custom Teflon cell. After, Cu was displaced on the Zn/MPL/CP to create CuZn/MPL/CP. Cu has a higher standard reduction potential (E∘) compared to zinc, enabling the formation of CuZn binary catalysts through galvanic displacement. Four different types of CuZn catalysts were prepared by using various displacement solutions containing different Cu anions such as copper chloride (CuCl2), copper sulfate (CuSO4), copper nitrate (CuNO3), and copper acetate (Cu(CH3COO)2).For the co-reduction reaction performance evaluation, experiments were conducted in a flow cell where CO2 was introduced as a gas, and the electrolyte contained NO3 –. Gas products were detected using gas chromatography, while liquid products were identified using 1H nuclear magnetic resonance. N-containing liquid products were detected via UV-vis spectroscopy using colorimetric methods. Specifically, urea was detected using the diacetyl monoxime method, confirming urea formation on the synthesized catalysts. It was observed that the amount of urea produced varied depending on the different CuZn catalysts. Figure 1

Fabrication of Al/Ni core–shell pigments via galvanic displacement and their application in radar-infrared compatible stealth coatings

The Al/Ni magnetic core–shell pigments were successfully synthesized in this study using the galvanic displacement method. A dense nickel shell was formed on the surface of a flake Al pigment (Al:Ni2+ = 1:0.5), resulting in a decrease in its lightness by 9 units while only slightly increasing the average infrared emissivity by 0.1 compared with the uncoated flake Al pigments. And it also exhibited soft magnetic characteristics, with a saturated magnetization value of 4.5 emu/g. Moreover, the impact of Al/Ni core-shell pigments on the infrared-radar stealth performance of the target was investigated based on the structure of “low-emissivity coating (LEC) + radar absorbing coating (RAC)”. The results showed that the emissivity of Al/Ni composite coatings maintained a low infrared emissivity (ε ≤ 0.23). The introduction of Ni shell improved the impedance matching between the Al/Ni coating and free space, allowing greater penetration of microwaves into the LEC and improving radar stealth performance of materials. The Al/Ni composite coatings (Al:Ni2+ = 1:0.5, the thickness of RAC:1.2 mm, and LEC: 60 μm) exhibited an extended effective absorption bandwidth (Reflection loss (RL) ≤ −10 dB) from 2.6 to 4.25 GHz and an enhancement of the average RL from −6.43 to −7.1 dB in the range of 2–18 GHz compared to the RAC. Consequently, the Al/Ni magnetic core–shell pigments can be used as novel low-emissivity pigments for infrared-radar compatible stealth research.

Evaluation of Nickel-Iron (Oxy)Hydroxide Catalysts in Varied Electrode Geometries Under Industrially Realistic Conditions for Enhanced Alkaline Water Electrolysis

In pursuit of realizing a hydrogen-based economy, the challenge lies in enhancing the efficiency of crucial water electrolysis technologies. Alkaline water electrolysis (AWE) holds promise as an ecologically friendly method for H2 production, primarily due to its capacity for employing non-precious metals as electrocatalysts, in contrast to more costly options which can only switch to noble metals such as ruthenium or iridium. However, this technology faces a significant challenge arising from the sluggish kinetics of the oxygen evolution reaction (OER), which constrains the overall efficiency. [1] Furthermore, the limited stability of many OER catalysts alternatives developed at lab scale and less harsh conditions poses a substantial obstacle to the commercialization of this technology.[2] To overcome this issue, the development of highly active OER catalysts that maintain their activity under industrial conditions is of major importance explaining the growing attention that this topic is gaining in literature. Nevertheless, most of the reported systems are tested at low current densities under easily manageable conditions in the laboratory (≤ 100 mA cm-2, 1 M KOH, RT). Without disagreeing that this approach is necessary to identify promising options among the numerous catalyst systems, it is not sufficient when competing with existing technologies that already achieve high current densities. In this context, we investigate a low-cost, abundantly available non-precious metal based OER-catalyst under industrially relevant conditions (≤ 1.2 A cm-2, 30 wt.-% KOH, 80 °C). The synthesis is based on a multistep galvanic deposition method introduced by Wu et al [3], receiving a highly porous NiFeOOH catalyst. Addressing the complexity of the multiphase process of AWE that involves gas-liquid-solid interfaces, the catalyst system is transferred to numerous nickel electrodes with different 3D geometries (plain woven mesh, knitted mesh, expanded metal mesh) for the investigation of their impact on bubble formation and detachment. To further optimize the catalyst system a variation of the iron content with respect to its’ molar fraction relatively to nickel has been carried out from x(Fe)=0 to x(Fe)=0.75, which after synthesis were first examined using SEM and EDS. The structure can be considered as pompom-shaped particles, forming a porous framework, as can be seen exemplarily in Figure 1a) on a knitted nickel-wire mesh coated with NiFeOOH. Observing variations in iron content, it becomes evident that a higher iron content results in larger particle sizes, thereby altering pore sizes. However, the surface morphologies of each catalyst until a molar fraction x(Fe)=0.5 is reached, can be considered as very similar. When comparing the SEM images of the mesh with a molar fraction x(Fe)=0.75 to the other molar fractions, a secondary phase becomes apparent on the surface. Notably, the porous structure persists within the crystalline phase. It could be shown by EDS that the target values for the molar fractions set in the galvanic bath and the actual molar fractions nearly show no deviations. Further, a uniform dispersion of Ni, Fe and O is observed.The electrochemical investigation of the prepared catalysts was done in a 3-electrode PTFE beaker cell setup in 30 wt % KOH and at 80 °C. The measurement protocol we introduce consists of galvanostatic steps between 0-1.2 A cm-2. The stability is tested chronopotentiometrically as well by maintaining a current density of 500 mA cm-2 for 100 h. It becomes apparent that no optimum is reached in the tested range of iron content and that the potential continues to drop as the molar fraction of Fe increases, achieving the lowest potential with 1.38 V vs. RHE at 50 mA cm-2 and 1.42 V vs. RHE at 750 mA cm-2 with x(Fe)=0.75. It could be further proved that the NiFeOOH catalyst with x(Fe)=0.75 is a highly stable catalyst, resulting in a potential increase of 27 mV over 100 h of testing at 500 mA cm-2, making it to an appropriate OER catalyst for the application in the AWE. The highly porous structure is maintained after testing, proved by SEM imaging. The iron contents after testing are also very similar, which means that there is almost no iron loss in the coating. For the different tested electrode geometries coated with NiFeOOH (x(Fe)=0.5), similar activity is observed, shown in Figure 1b) with a ranging potential between 1.38 V to 1.41 V vs. RHE at 50 mA cm-2 and 1.42 V to 1.45 V vs. RHE at 750 mA cm-2.[1] a) Cao et al., Energy Environ. Sci. 2012 b) Zhao et al., ACS Chemical Reviews 2023.[2] Zeng et al., Journal of Energy Chemistry 2022.[3] Wu et al., Applied Surface Science 2021. Figure 1

Unexpected self-driven enhanced leaching mechanism of cathodes and anodes from end-of-life lithium-ion battery

The fast growth of the energy storage and electric vehicle industries in recent years has produced an enormous amount of end-of-life (EoL) lithium-ion batteries (LIBs). To achieve faster leaching kinetics, traditional hydrometallurgical recovery of EoL LIBs cathodes requires complex pre-treatment processes to liberate cathode active powders from cathode sheets. Nevertheless, utilizing the cathode sheets rather than the cathode powders results in unexpected enhanced leaching of EoL LIBs during the initial stage. To reveal the mechanism for this unexpected phenomenon, a series of electrochemical experiments are designed. The self-driven enhanced leaching mechanism is proposed and verified with delicately designed electrochemical experiments and thermodynamic calculations. Based on this mechanism, an innovative galvanic cell recovery method is constructed to achieve effective leaching of valuable metals from both cathode and anode sheets simultaneously without chemical reducing agents and complex pre-treatment processes. This research provides novel ideas for the comprehensive recycling of EoL LIBs to improve economics and environmental sustainability.

An experimental campaign for assessing the role of tensioned tendons on the shear capacity of half-joints

An important percentage of bridges and viaducts constituting the Italian road infrastructures dates back to the years 50s and 60s and is characterized by prestressed r.c. decks adopting half-joints for obtaining statically determinate schemes. In existing bridges, half-joints are often subjected to degradation phenomena, mostly promoted by water percolation and stagnation, which led to classify the bridge in a high attention class, according to the Italian Guidelines for Risk Classification and Management, Safety Assessment and Monitoring of Existing Bridges. Furthermore, half-joints are difficult to inspect and to maintain. The current safety assessment procedures at ultimate limit state are based on simplified Strut&Tie models that usually neglect the contribution of prestressing tendons anchored in the half-joints on the resisting mechanisms and the ultimate capacity. This work presents the design of an experimental campaign for investigating the shear behaviour and the ultimate capacity of half-joints in which inclined prestressed tendons are anchored. In detail, six laboratory scaled post-tensioned beams are built with half-joints in correspondence of the support regions, dimensioned on the basis of a real bridge girder and numerical 3D finite element nonlinear analyses. The main research goal is to evaluate the influence of tendons on the half-joints capacity by comparing results with those obtained from specimens with non-tensioned tendons and without tendons. Three levels of pre-tensions in specimens characterized by the same reinforcements are considered. In addition, for one level of pre-tension, the effects of different half-joints detailing are investigated. Finally, the role of degradation due to ageing is also addressed by inducing corrosion in one specimen through a galvanic method.

Влияние защитного покрытия на процессы коррозии металлических контейнеров для иммобилизации высокоактивных радиоактивных отходов

The article explores nickel-based protective coatings and their influen e on high-temperature changes occurring on the inner surface of steel containers designed for HLW immobilization provided their interaction with the melts of model waste form materials. It evaluates the corrosion behavior of container surfaces with a nickel-based protective coating depending on its application method, i.e., galvanic and chemical. The study indicates the factors governing the corrosion depth, i.e., the depth to which the container steel surface may get altered depending on 4 different waste form material compositions. The study demonstrates high efficien y of the galvanic method in terms of nickelbased protective coating application and the major influen e that high sodium and calcium content has on the depth of corrosion penetration into container surface.

Enhanced Fault Type Detection in Covered Conductors Using a Stacked Ensemble and Novel Algorithm Combination.

This study introduces an innovative approach to enhance fault detection in XLPE-covered conductors used for power distribution systems. These covered conductors are widely utilized in forested areas (natural parks) to decrease the buffer zone and increase the reliability of the distribution network. Recognizing the imperative need for precise fault detection in this context, this research employs an antenna-based method to detect a particular type of fault. The present research contains the classification of fault type detection, which was previously accomplished using a very expensive and challenging-to-install galvanic contact method, and only to a limited extent, which did not provide information about the fault type. Additionally, differentiating between types of faults in the contact method is much easier because information for each phase is available. The proposed method uses antennas and a classifier to effectively differentiate between fault types, ranging from single-phase to three-phase faults, as well as among different types of faults. This has never been done before. To bolster the accuracy, a stacking ensemble method involving the logistic regression is implemented. This approach not only advances precise fault detection but also encourages the broader adoption of covered conductors. This promises benefits such as a reduced buffer zone, improved distribution network reliability, and positive environmental outcomes through accident prevention and safe covered conductor utilization. Additionally, it is suggested that the fault type detection could lead to a decrease in false positives.

A Data Set of Signals from an Antenna for Detection of Partial Discharges in Overhead Insulated Power Line

We introduce a data set obtained via a contactless antenna method for detecting partial discharges in XLPE-covered conductors used in medium-voltage overhead power transmission lines. The data set consists of almost three years’ worth of data, collected every hour from 9 measuring stations in Czechia and Slovakia. Each sample in the data set represents a single signal gathered for 20 ms. The contactless method is deployed on the same stations as the galvanic contact method, which is used by power distributors and can provide ground truth. Also manually curated data by human expert are present. Successful detection of partial discharges can prevent electricity shutdowns and forest fires resulting from insulation failure due to vegetation contact. The data set is particularly relevant for covered conductors used in mountainous regions where establishing a safe zone is challenging. The contactless method offers advantages such as cheaper and easier installation. The data set has the potential to develop machine learning models to detect partial discharges and facilitate safer and cheaper use of covered conductors.

Ag-Cu Nanoparticles as Cathodic Catalysts for an Anion Exchange Membrane Fuel Cell

In this work, the synthesis of bimetallic Ag and Cu particles on carbon vulcan (AgCu/C) is reported, synthesized by a simple galvanic displacement method using citrate tribasic hydrate as a co-reducing agent and a commercial material based on Cu/C as a template. The materials were characterized by several physicochemical techniques, including TGA, ICP-OES, XRD, SEM, and BET. The catalysts were evaluated as cathodic catalysts for the oxygen reduction reaction (ORR) and were used for the preparation of membrane electrode assemblies for evaluation in an Anion Exchange Membrane Fuel Cell (AEMFC). The results were compared with the commercial Ag/C and Cu/C catalysts; the bimetallic catalyst obtained a higher power density, which was attributed to a synergistic effect between Ag and Cu particles.

Three-Dimensional Au(NiMo)/Ti Catalysts for Efficient Hydrogen Evolution Reaction.

In this study, NiMo catalysts that have different metal loadings in the range of ca. 28-106 µg cm-2 were electrodeposited on the Ti substrate followed by their decoration with a very low amount of Au-crystallites in the range of ca. 1-5 µg cm-2 using the galvanic displacement method. The catalytic performance for hydrogen evolution reaction (HER) was evaluated on the NiMo/Ti and Au(NiMo)/Ti catalysts in an alkaline medium. It was found that among the investigated NiMo/Ti and Au(NiMo)/Ti catalysts, the Au(NiMo)/Ti-3 catalyst with the Au loading of 5.2 µg cm-2 gives the lowest overpotential of 252 mV for the HER to reach a current density of 10 mA·cm-2. The current densities for HER increase ca. 1.1-2.7 and ca. 1.1-2.2 times on the NiMo/Ti and Au(NiMo)/Ti catalysts, respectively, at -0.424 V, with an increase in temperature from 25 °C to 75 °C.

Investigation of the economic and sustainability aspects of cathodic protection method for corrosion prevention in marine structures

Assessment of sustainability of structures requires calculation of life-cycle environmental and economic impacts. In this study, it is aimed to investigate economic value contribution of corrosion prevention, provided by galvanic cathodic protection method during the use life of marine structures, with consideration of sustainability. For a real wharf structure, cost of galvanic cathodic protection during the economic life of the structure and cost–benefit analysis of corrosion prevention are presented, and a method is proposed for understanding its economic contribution. Based on a real wharf structure’s design and corrosion protection calculations, and considering a use life of approximately 50 years, average loss of material due to corrosion is 0.16 mm/year, in absence of cathodic protection. Thus, for the wharf structure under investigation (two segments each 10 m × 45 m size supported by a total of 100 piles with diameter 100 cm and depth varying between 34–40 m), loss of material is estimated for each pile as 95 kg/year, totalling 475 tons for 100 piles in 50 years. This loss may lead to strengthening requirements for the structure. Comparing costs of strengthening with 91.1 tons of Al–Zn–In anode that would be spent for cathodic protection, economic gains can be estimated as 285,000 USD.

Hybrid Composite of Subnanometer CoPd Cluster-Decorated Cobalt Oxide-Supported Pd Nanoparticles Give Outstanding CO Production Yield in CO2 Reduction Reaction

Catalytic carbon dioxide (CO2) hydrogenation to carbon monoxide (CO) via reverse water-gas shift (RWGS) reaction is of particular interest due to its direct use in various industrial processes as feedstock. However, the competitive CO2 methanation process severely limits the RWGS reaction in a lower temperature range. In this context, we propose a novel nanocatalyst (NC) comprising oxygen vacancy-enriched subnanometer-scale CoPd hybrid cluster (CoOxVPd)-anchored Pd nanoparticles (NPs) on cobalt oxide support underneath (denoted as CP-CoOxVPd) by using a galvanic replacement reaction-assisted wet chemical reduction method. As-developed CP-CoOxVPd NC initiated the RWGS reaction at 423 K temperature while showing an optimum CO production yield of ∼3414 μmol g−1catalyst and a CO selectivity as high as ∼99% at 523 K in the reaction gas of CO2:H2 = 1:3. The results of physical characterizations along with electrochemical and gas chromatography (GC) suggest that abundant oxygen vacancies in the surface-anchored CoOxVPd clusters are vital for CO2 adsorption and subsequent activation, while neighboring Pd domains facilitate the H2 dissociation. The obtained results are expected to provide a feasible design of Co-based NCs for the RWGS reaction.

Composite Coatings of Chitosan and Silver Nanoparticles Obtained by Galvanic Deposition for Orthopedic Implants.

In this work, composite coatings of chitosan and silver nanoparticles were presented as an antibacterial coating for orthopedic implants. Coatings were deposited on AISI 304L using the galvanic deposition method. In galvanic deposition, the difference of the electrochemical redox potential between two metals (the substrate and a sacrificial anode) has the pivotal role in the process. In the coupling of these two metals a spontaneous redox reaction occurs and thus no external power supply is necessary. Using this process, a uniform deposition on the exposed area and a good adherence of the composite coating on the metallic substrate were achieved. Physical-chemical characterizations were carried out to evaluate morphology, chemical composition, and the presence of silver nanoparticles. These characterizations have shown the deposition of coatings with homogenous and porous surface structures with silver nanoparticles incorporated and distributed into the polymeric matrix. Corrosion tests were also carried out in a simulated body fluid at 37 °C in order to simulate the same physiological conditions. Corrosion potential and corrosion current density were obtained from the polarization curves by Tafel extrapolation. The results show an improvement in protection against corrosion phenomena compared to bare AISI 304L. Furthermore, the ability of the coating to release the Ag+ was evaluated in the simulated body fluid at 37 °C and it was found that the release mechanism switches from anomalous to diffusion controlled after 3 h.

Investigation on M@CuOx/C (M=Ru, Rh, Pd and Pt) catalysts prepared by galvanic reduction for hydrogen evolution from ammonia borane

The development of a cost-effective catalyst for hydrogen evolution from ammonia borane is of importance for the application of AB as a hydrogen storage material. In this manuscript, a series of noble metal catalysts M@CuOx/C (M = Ru, Rh, Pd, and Pt) are prepared by the galvanic reduction method. The catalysts are characterized by XRD, TEM, EDS mappings and lines scanning, XPS, HAADF-STEM, and ICP-OES. The noble metal is highly dispersed on the surface of Cu nanoparticles. The morphology of Cu nanoparticles changed according to different metals after the introduction of noble metal and there has an interaction between the noble metal and Cu. The M@CuOx/C is used for the hydrolysis of AB. For the same metal catalyst, the activity of M@CuOx/C is increased by about 3–7 times than the corresponding M/C at 298 K. The Rh shows the highest TOF and lowest activation energy among the four noble metals.

Study Experimental the Effect of Normalizing Treatment and Galvanic Pack Carburizing Process on Mechanical Properties of Low Carbon Steel

Steel is the type of metal most often used in engineering. This study aimed to improve the mechanical properties of mild steel in terms of hardness, ductility, and other mechanical properties and to compare the hardness of carburized steel by galvanic treatment with non-galvanic carburizing of the steel. This research was carried out by varying the heat treatment process, namely carburizing with galvanic heat treatment and carburizing without galvanic, where the carburizing process uses activated carbon coconut shell charcoal with a weight percentage of 80% and 20% of K2CO3 (Potassium Carbonate) at a temperature of 9000C with a holding time of 60 minutes, 120 minutes and 180 minutes. The results obtained from this study indicate that the mechanical properties (hardness) of carbon steel increase at a temperature of 9000C with a holding time of 1 hour on the galvanic heating method with a better hardness value than the hardness of steel on the non-galvanic method. The hardness value obtained in the galvanic method is 94.06 HRB, while in the non-galvanic method, it is 76.4 HRB. And the pearlite phase is formed, increasing the hardness value on the surface of the specimen.

Proposal of a Galvanic Corrosion Evaluation Method That Can Reproduce the Environment of Deicing Salt Spraying Areas

Proposal of a Galvanic Corrosion Evaluation Method That Can Reproduce the Environment of Deicing Salt Spraying Areas

Partial oxidation of methane to oxygenates by oxygen transfer at novel lattice oxygen sites of palladium and ruthenium bimetal oxide

Alumina-supported bimetal oxide (PdRuOx) catalysts were prepared by galvanic displacement reduction method for partial oxidation of methane into oxygenates, and evaluated in a fixed-bed reactor at relatively low temperatures of 280–310 °C, using a mixture of NO and O2 as the oxidant. The bimetal oxide catalysts exhibited high selectivity to HCHO. However, CO2 was dominantly obtained over two alumina-supported monometal oxide (PdO and RuO2) catalysts. Characterizations results showed that bimetal oxide-PdRuOx species with Pd-(O)-Ru active sites can selectively convert CH4 to HCHO through the transfer of its novel lattice oxygen. And in this process, CH3OH may play as an intermediate. Compared to oxidation with either O2 and NO, the mixture oxidant of NO and O2, acting as an oxygen shuttle through the gas-phase reaction of NO+1/2 O2→NO2, promoted the selective formation of HCHO.

In Vitro Corrosion Assessment of the Essure® Medical Device in Saline, Simulated Inflammatory Solution and Neutral Buffered Formalin

The Essure® permanent contraceptive implant, comprised of four alloys (nickel-titanium, 316L stainless steel, platinum-iridium, and tin-silver solder) and Dacron (PET) fibers, has been approved for use in the US for about two decades. However, little has been published on this implant's biomaterials performance, and as this implant gains interest in terms of in vivo performance, methods of implant post-retrieval storage also need to be assessed. This study investigated the electrochemical properties and ion release profile of Essure® during storage in phosphate buffered saline (PBS), 10 mM H2O2/PBS, a simulated inflammatory solution, and 10% neutral buffered formalin (NBF) to investigate the corrosion behavior and metal ion release. First, a galvanic test method was used to measure the galvanic interactions between alloys within the device. Second, an ion-release study over 107 days was performed. Ions were measured using inductively-coupled plasma mass spectrometry and the implants were assessed using digital optical microscopy, scanning electron microscopy, and energy dispersive x-ray spectrometry. The tin-silver (SnAg) solder continuously corroded in PBS and H2O2/PBS. In the presence of H2O2, nickel and titanium ions were released from the nickel-titanium (NiTi) coil, whereas release of these ions was minimal in PBS alone. Overall, corrosion of the SnAg solder, which holds the NiTi and 316L SS together, was significant in both PBS and H2O2/PBS and may result in loss of connection of the NiTi and 316L stainless steel portions of the implant. Storage in NBF exhibited very low corrosion rates for all alloys and low levels of ion release were observed indicating that formalin storage minimally affects the implant's corrosion status. Statement of significanceThe Essure® device is an FDA premarket-approved female permanent sterilization device containing four different metal alloys and poly(ethylene terephthalate) polymer fibers. Significant concerns related to this device have been raised by the FDA since its introduction in 2002. This study is the first published in vitro work to specifically assess the corrosion mechanisms in this multi-alloy device and the role of different solution environments, including formalin storage, inorganic physiological saline and a simulated inflammatory condition. Significant evidence of corrosion of the tin-silver solder is documented, the release of Ni and Ti under simulated inflammatory conditions, and the relative inertness of storage of these implants in neutral buffered saline is presented. The tin-silver corrosion corroborates recent clinical evidence of tin corrosion products in tissues adjacent to these devices in vivo.

In vitro antimicrobial effect of titanium anodization on complex multispecies subgingival biofilm

Anodization is a routine industrial galvanic method that produces a titanium oxide layer on the surface of titanium. Considering the possibility that this technique could influence microbial adsorption and colonization, this in vitro study was conducted to evaluate the impact of a process of anodization applied to a titanium surface on the microbial profile of multispecies subgingival biofilm. Titanium discs produced by using two different processes—conventional and Anodization—were divided into two groups: conventional titanium discs with machined surface (cpTi) Control Group and titanium discs with anodic oxidation treatment (anTi) Test Group. Subgingival biofilm composed of 33 species was formed on the titanium discs that were positioned vertically in 96-well plates, for 7 days. The proportions and the counts of microbial species were determined using a DNA–DNA hybridization technique, and data were evaluated using Mann-Whitney test (p < 0.05). Mean total bacterial counts were lower in Test Group in comparison with Control Group (p < 0.05). Nine bacterial species differed significantly, and were found in higher levels in Control Group in comparison with Test Group, including T. forsythia, E. nodatum, and F. periodonticum. In conclusion, titanium discs with anodization could alter the microbial profile of the biofilm formed around them. Further clinical studies should be conducted to confirm the clinical impact of these findings.

Synthesis of hollow structured PtNi/Pt core/shell and Pt-only nanoparticles via galvanic displacement and selective etching for efficient oxygen reduction reaction

This study uses a simple galvanic displacement-acid etching method for synthesizing PtNi nanoparticles with different morphologies and surface properties. Core/shell structured Ni/PtNi nanoparticles were prepared from nickel nanoparticles subjected to a galvanic displacement reaction with Pt ions. By controlling the dealloying conditions, hollow PtNi/Pt core/shell (H-PtNi/Pt) and Pt-only (H-Pt) nanoparticles could be formed. The H-PtNi/Pt catalyst showed the highest oxygen reduction reaction (ORR) mass and specific activities (0.8 A mg−1Pt and 1520 μA cm−2Pt at 0.9 VRHE), which were 3.33- and 5.67-times higher than those of commercial Pt/C. It revealed that forming a PtNi/Pt core/shell structure with a hollow morphology plays an important role for enhancing ORR activity. The H-PtNi/Pt catalyst also showed a very low degradation in specific activity of less than 1% after extensive potential cycling (10,000 cycles) due to the stable platinum outer layer covering the hollow PtNi alloy structure.